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From: Mark Rutland <mark.rutland@arm.com>
To: linux-arm-kernel@lists.infradead.org, will@kernel.org,
	catalin.marinas@arm.com
Cc: james.morse@arm.com, mark.rutland@arm.com, maz@kernel.org
Subject: [PATCH 06/14] arm64: entry: add a call_on_irq_stack helper
Date: Mon, 10 May 2021 16:56:13 +0100	[thread overview]
Message-ID: <20210510155621.52811-7-mark.rutland@arm.com> (raw)
In-Reply-To: <20210510155621.52811-1-mark.rutland@arm.com>

When handling IRQ/FIQ exceptions the entry assembly may transition from
a task's stack to that CPU's IRQ stack (and IRQ shadow call stack).

In subsequent patches we want to migrate the IRQ/FIQ triage logic to C,
and as we want to perform some actions on the task stack (e.g. EL1
preemption), we need to switch stacks within the C handler. So that we
can do so, this patch adds a helper to call a function on a CPU's IRQ
stack (and shadow stack as appropriate).

Subsequent patches will make use of the new helper function.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
---
 arch/arm64/include/asm/exception.h |  2 ++
 arch/arm64/kernel/entry.S          | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h
index 3a859d4e8b59..c24b69c0c589 100644
--- a/arch/arm64/include/asm/exception.h
+++ b/arch/arm64/include/asm/exception.h
@@ -40,6 +40,8 @@ asmlinkage void el0_error_compat_handler(struct pt_regs *regs);
 
 asmlinkage void noinstr enter_el1_irq_or_nmi(struct pt_regs *regs);
 asmlinkage void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs);
+asmlinkage void call_on_irq_stack(struct pt_regs *regs,
+				  void (*func)(struct pt_regs *));
 asmlinkage void enter_from_user_mode(void);
 asmlinkage void exit_to_user_mode(void);
 void arm64_enter_nmi(struct pt_regs *regs);
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 8c7ddd651756..327a559679f7 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -979,6 +979,42 @@ SYM_CODE_START(ret_from_fork)
 SYM_CODE_END(ret_from_fork)
 NOKPROBE(ret_from_fork)
 
+/*
+ * void call_on_irq_stack(struct pt_regs *regs,
+ * 		          void (*func)(struct pt_regs *));
+ *
+ * Calls func(regs) using this CPU's irq stack and shadow irq stack.
+ */
+SYM_FUNC_START(call_on_irq_stack)
+#ifdef CONFIG_SHADOW_CALL_STACK
+	stp	scs_sp, xzr, [sp, #-16]!
+	adr_this_cpu scs_sp, irq_shadow_call_stack, x17
+#endif
+	/* Create a frame record to save our LR and SP (implicit in FP) */
+	stp	x29, x30, [sp, #-16]!
+	mov	x29, sp
+
+	ldr_this_cpu x16, irq_stack_ptr, x17
+	mov	x15, #IRQ_STACK_SIZE
+	add	x16, x16, x15
+
+	/* Move to the new stack and call the function there */
+	mov	sp, x16
+	blr	x1
+
+	/*
+	 * Restore the SP from the FP, and restore the FP and LR from the frame
+	 * record.
+	 */
+	mov	sp, x29
+	ldp	x29, x30, [sp], #16
+#ifdef CONFIG_SHADOW_CALL_STACK
+	ldp	scs_sp, xzr, [sp], #16
+#endif
+	ret
+SYM_FUNC_END(call_on_irq_stack)
+NOKPROBE(call_on_irq_stack)
+
 #ifdef CONFIG_ARM_SDE_INTERFACE
 
 #include <asm/sdei.h>
-- 
2.11.0


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  parent reply	other threads:[~2021-05-10 16:00 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-10 15:56 [PATCH 00/14] arm64: entry: migrate more code to C Mark Rutland
2021-05-10 15:56 ` [PATCH 01/14] arm64: remove redundant local_daif_mask() in bad_mode() Mark Rutland
2021-05-10 15:56 ` [PATCH 02/14] arm64: entry: unmask IRQ+FIQ after EL0 handling Mark Rutland
2021-05-10 15:56 ` [PATCH 03/14] arm64: entry: convert SError handlers to C Mark Rutland
2021-05-10 15:56 ` [PATCH 04/14] arm64: entry: move arm64_preempt_schedule_irq to entry-common.c Mark Rutland
2021-05-10 15:56 ` [PATCH 05/14] arm64: entry: move preempt logic to C Mark Rutland
2021-05-10 15:56 ` Mark Rutland [this message]
2021-05-10 15:56 ` [PATCH 07/14] arm64: entry: convert IRQ+FIQ handlers " Mark Rutland
2021-05-10 15:56 ` [PATCH 08/14] arm64: entry: organise entry handlers consistently Mark Rutland
2021-05-10 15:56 ` [PATCH 09/14] arm64: entry: organise entry vectors consistently Mark Rutland
2021-05-10 15:56 ` [PATCH 10/14] arm64: entry: consolidate EL1 exception returns Mark Rutland
2021-05-10 15:56 ` [PATCH 11/14] arm64: entry: move bad_mode() to entry-common.c Mark Rutland
2021-05-10 15:56 ` [PATCH 12/14] arm64: entry: improve bad_mode() Mark Rutland
2021-05-10 15:56 ` [PATCH 13/14] arm64: entry: template the entry asm functions Mark Rutland
2021-05-10 15:56 ` [PATCH 14/14] arm64: entry: handle all vectors with C Mark Rutland

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